Part IV.] Caccia : Selection method of treatment in India. 349 
Less about one-third allowed for casualties and seed 
bearers . . ....... 10,660 
Balance of exploitable trees available for cutting . 21,000 
Average yearlv yield ..... 4,200 
Hi. — General Possibility Method. 
By dividing the total number of trees existing in certain girth 
(or diameter) classes by the number of years represented by those 
girth classes, a general possibility is obtained. Theoretically, 
the calculation may be made for the whole period of the rotation, 
and it may include all the trees existing in all the girth classes. 
Or, the general possibility may be merely calculated for a period 
equal to the number of years covered by a certain sequence of the 
higher girth classes. In addition corrections are made for casual- 
ties ; the extent of such corrections in each girth class depending on 
the kind of trees which it is proposed should count against the pos- 
sibility. As a rule the general possibility is based on the number of 
trees which it is calculated will survive to reach exploitable dimen- 
sions. The method of procedure may best be explained by a few 
examples. 
The disadvantages of a “ General Possibility ” are that the 
possibility has to be calculated for a long period, and in addition 
the exploitable age has to be determined, always a matter of great 
difficulty and uncertainty under the Selection System. 
For the application of this method in its simplest form, the 
prescriptions of the working plan for the Minhla forests of the 
Tharrawaddy Division, Burma,* may be taken into considera- 
tion. 
The only system on which the forest can at present be worked is that of 
“ selection fellings.” 
Example 1. Possibi- 
lity calculated for the The actual growing stock in the working circle is as 
whole period iff rota- follows : — 
tion. 
Trees. 
Trees above 2^ feet diameter ... .7 720 
Trees from 2 feet to 2| feet diameter .... 10,440 
Trees from 1^ feet to 2 feet diameter .... is'oso 
Trees from 1 foot to 14 feet diameter .... 27'390 
Trees below 1 foot diameter, dominant ... 36 570 
Trees below 1 foot diameter, suppressed ... 39 230 
Present stock of plantation, roughly estimated at 40 
per cent, of the original stock .... 284,000 
* Working Plan for the Minhla forest, 
Burma, by H. A. Hoghton, 1893. 
Tharrawaddy Division, Pegu Circle, 
